Assessment of the physiological and biochemical characterization of a Lactic acid bacterium isolated from chicken faeces in sahelian region

The aim of this work was the examination of the microbiological and technological properties of a lactic acid bacterium (CWBI-B623) isolated from chicken faeces in sahelian region (Burkina Faso). The strain CWBI-B623 is a Gram positive rod, asporogenous, catalase-positive, facultatively anaerobic, non motile and mesophilic. The analysis showed that it produce L(+)-lactic acid via homofermentative pathway and it was able to ferment an important number of the carbohydrates of API 50CHL system. The 16S-rDNAsequence analysis revealed that the isolate was phylogenetically a member of the genus Lactobacillus and formed a subline within the Lactobacillus casei cluster. The minimal inhibitory concentration of CWBI-B623 for bile salts was higher than 1% and the survival rates to acidity with pH 3.0 and pH 2.5 were 26 and 1.2%, respectively. CWBI-B623 is an Lactobacillus casei species based on its physiological and biochemical properties and it could be a good candidate for probiotic formulations.Key words: Lactic acid bacteria, Lactobacillus, probiotic, biodiversity

The Resistance to Freeze-Drying and to Storage Was Determined as the Cellular Ability to Recover Its Survival Rate and Acidification Activity

The protective effects of the fatty acid composition and membrane action of the acidification activity of two strains of Lactobacillus kept at 20°C were studied. The addition of sorbitol, monosodium glutamate and glycerol during storage is causing the decline of acidification and increased concentrations of unsaturated fatty acids observed in both strains. The addition of sorbitol and monosodium glutamate does not alter the fatty acid composition, whatever the strain, but increases the resistance to freeze-drying of L. plantarum CWBI-B1419 and improves survival during storage. The addition of these preservatives and decreased activity of acidification improves the ratio unsaturated. These results indicate that the survival during storage and freeze-drying resistance are closely related to the composition of membrane fatty acids. This behaviour can be interpreted as an adaptation of L. plantarum B1419-CWBI supplemented by cryoprotectant additives such as sorbitol or monosodium glutamate sorbitol and monosodium glutamate as an additive. L. plantarum CWBI-B1419 presents a greater adaptation to culture conditions than L. paracasei ssp. paracasei LMG9192T

Polyphasic Identification Of A New Thermotolerant Species Of Lactic Acid Bacteria Isolated From Chicken Faeces

peer reviewedTwo thermotolerant and desiccation tolerant lactic acid bacteria (TDLAB) were pointed out from twenty isolated strains from soils and dried chicken faeces. Samples were collected in poultry farms in the vicinity of Dakar, Senegal (West Africa). The two new isolates were called Sp.4 (Sp.4=CWBI-B534=LMG7278) and Sp.20 (Sp.20=CWBI-B545=LMG7279). They are Grampositive, catalase-negative, facultatively anaerobic, non-motile, and non-spore-forming rods. Both produce D/L lactic acid via homofermentative pathway. Growth of the strains occurred between 15°C and 44°C. The optimum temperature for growth was in 30°C-37°C temperature and pH 3-8 range. Desiccation treatment in glycerol showed 30% survival rates. Complex total fatty acid pattern of the strains showed the presence of C14:0, C16:0, C16:1, C18:0, C18:1, C18:2, C18:3. SDS-PAGE of total protein of both strains placed them in L. plantarum group. AFLP analysis showed a phylogenetic proximity of the two strains with L. plantarum stricto sensu species. Specific amplified 16s rDNA restriction analysis (ARDRA) of the 16S rDNA gene, however, showed that these thermotolerant strains were not L. plantarum. ITS sequencing revealed that Sp.20 (LMG 7279) could be classed into Lactobacillus paraplantarum species since the short sequence of ITS showed 95% of similarity with reference species. Polyphasic identification shows that Sp.4, (the type strain is LMG 7278T) represent a new species within the genus Lactobacillus with only 88%+/-1 ITS sequence similarity with reference species. For which the name Lactobacillus aminata sp. nov. is proposed

Les entérocoques : avantages et inconvénients en biotechnologie (synthèse bibliographique)

Enterococci: advantages and drawbacks in biotechnology, a review. Enterococci are lactic acid bacteria that have been used for centuries in food processing. These microorganisms play a vital role in conservation (extension of shelf life) and in the bacteriological quality of food while keeping their nutritional and organoleptic properties. However, Enterococcus faecium and Enterococcus faecalis are indicators of faecal contamination and are also implicated in nosocomial diseases. The genetic plasticity (transfer of genetic elements) of these bacteria allows them not only to adapt to various ecosystems, but also to be vehicles of antibiotic resistances and bacterial virulence, which is of public health concern. Thus, the use of enterococci in the food industry is becoming controversial. However, enterococci are also involved in the fermentation of many foods (milk, vegetables, meats or fish) and are able to produce various antimicrobial molecules (e.g. lactic acid, bacteriocins or hydrogen peroxide) that make them indispensable in the food industry. Their use as probiotic must therefore be carefully characterized in order to prove their safety. The wide range of bacteriocins (enterocins) found in these bacteria could also be valorized by developing purification methods to replace the bacterial strains themselves by their enterocins in foodstuffs, therefore eliminating the risk of direct use of bacteria

In Vitro Detection And Characterization Of Bacteriocin-Like Inhibitory Activity Of Lactic Acid Bacteria (Lab) Isolated From Senegalese Local Food Products

The prevalence of lactic acid bacteria (LAB) in Senegalese local food products was determined to be 109 CFU/g in millet flour and milk products, and 103 CFU/g in seafood products. These food products are generally preserved by spontaneous fermentation (without addition of starters). Of 220 lactic acid bacteria strains randomly selected from such products, 12 isolates capable of producing bacteriocin-like substances (bac+) were detected. Based on the use of API 50 CH test kits and 16S rDNA sequencing, 11 isolates were characterized as Lactococcus lactis subsp. lactis strains and one as an Enterococcus faecium strain. Nisin- and enterocin B-encoding genes were respectively identified in the bac+ lactococcal strains and the E. faecium strain. Since the bac+ Lc. lactis strains were isolated from different products, it suggests a high potential of growth by these strains in variable ecological environments. Expression of the nisin gene was indicated for one of the lactococcal strains, designated Lc. lactis subsp. lactis CWBI-B1410, which showed the highest in vitro antibacterial activity. An antibacterial preparation prepared from the CWBI-B1410 strain showed many similarities with nisin with regards to its inhibitory effects, heat resistance, protease sensitivity profile, as well as retention time of the antibacterial substances on a C18 column. These results suggest that a nisin-like substance is produced by the CWBI-B1410 strain. This strain has been selected for application as an additional barrier to supplementation with sodium chloride as a means to improve the bacterial quality of fish commodities in Senegal

Sélection d'un complexe enzymo-bactérien antagoniste de Campylobacter ssp. pour l'élevage, sur parcours extérieur, de poulets de chair - Rapport final

Sélection d’un complexe enzymo-bactérien antagoniste de Campylobacter ssp. pour l’élevage, sur parcours extérieur, de poulets de chai

Sélection d'un complexe enzymo-bactérien antagoniste de Campylobacter ssp. pour l'élevage, sur parcours extérieur, de poulets de chair - Rapport final

Sélection d’un complexe enzymo-bactérien antagoniste de Campylobacter ssp. pour l’élevage, sur parcours extérieur, de poulets de chai

Recherche d'un probiotique travaillant en synergie avec une hémicellulase en alimentation avaire - Rapport scientifique final

Recherche d'un probiotique travaillant en synergie avec une hémicellulase en alimentation aviair

Characterization of lactic acid bacteria isolated from poultry farms in Senegal

peer reviewedThe group that includes the lactic acid bacteria is one of the most diverse groups of bacteria known and these organisms have been characterized extensively by using different techniques. In this study, thirty lactic acid bacterial strains were isolated from soils chicken faeces and feathers. A total of nineteen isolates were obtained and by sequential screening for catalase activity and Gram-staining, eight were determined to be LAB out of which six were established to be homofermentative by the gel plug test. Five isolates were identified by use of the API 50CHL kit and four Lactobacilli strains and one Lactococci strain were selected to study their growth and lactic acid production profiles in a time course experiment. The Lactobacilli strains, both isolated from faeces, produced higher amounts of cells and lactic acid from soils as compared to the lactococci strain isolated from feathers. L (+)-lactic acid is the only optical isomer for use in pharmaceutical and food industries because is only adapted to assimilate this form. The optical isomers of lactic acid were examined by L (+) and D (-) lactate dehydrogenase kit. Lactobacilli strains produced combination of both optical isomers of lactic acid. Among them, Lactobacillus casei subsp. casei produced the low amount of D (-)-lactic (2%). The optimum rates of glucose for lactic acid production by Lactobacillus strains were 180 and 120 g/l for Lactobacillus plantarum and Lactobacillus paraplantarum, respectively